My invention improves upon currently available self-loading tow dollies by permitting dolly components to be replaced without requiring cutting or welding. It also improves upon currently available self-loading tow dollies by reducing the overall weight of a tow dolly and by preventing rotational component seizures through improved lubricant coverage within rotating components.
Tow truck operators commonly use self-loading tow dollies. When a tow truck tows a vehicle it lifts one end of the vehicle. To prevent damage to the towed vehicle, for example, a four wheel drive vehicle that is stuck in gear, tow truck operators use tow dollies to lift the opposite end of the towed vehicle so that the dolly's wheels contact the road instead of the towed vehicle's wheels. Removing all of the towed vehicle's wheels from the ground greatly diminishes the possibility of damage to the towed vehicle.
Those skilled in the art know that tow dollies for raising pairs of coaxial vehicle wheels typically employ a pair of frame-like bases for supporting pairs of dolly wheels. Such dolly bases are placed outside two vehicle wheels to be lifted or elevated; the two bases being cross connected by parallel spaced tubular axles which are typically longitudinally adjustable to accommodate variations in vehicle wheel lateral spacing. Suitable mechanisms are provided for positioning the dolly wheels between a lowered position and a raised towing position which serves to elevate the towed vehicle prior to the actual towing operation. Suitable locking devices are provided for maintaining dolly wheels in desired elevated or lowered positions for storing or towing operations, respectively. Other known mechanisms without separate ratchet systems are employed for maintaining dolly wheels in elevated positions. U.S. Pat. No. 5,941,675 to Orr, fully incorporated herein by reference, shows and describes an exemplary tow dolly.
Tow dollies of the type described in U.S. Pat. No. 5,941,675 typically have several sections which are disengagable from one another for easy storage and transport of the tow dolly. For example, there are often two frame-like wheel assemblies where the dolly's wheels are mounted on spindle assemblies which are attached to the frame-like wheel assemblies. Brackets on the frame-like wheel assemblies accommodate axles that engage the wheels of the vehicle to be towed.
Tow dollies must have sturdy components that articulate in a manner when a car is lifted off the ground in just a few moments. Spindle assemblies are typically made of steel as are the brackets where the steel rail ends of the axles are fitted to complete assembly. This “steel on steel” construction permits steel dolly components to be welded together and has proved to be sturdy in the field. Over a period spanning more than thirty years the steel self-loading tow dolly has become the industry standard. Using all steel components and welding steel components together on the dolly frame results, however, in a heavy tow dolly that an operator must carry from the tow truck to the towed vehicle. Even when disassembled, the pieces of current tow dollies are heavy and cause strain on tow truck operators which may lead to back injuries and other health problems.
When tow truck operators hand carry self-loading tow dollies from and to a tow truck, weight is a key factor in eliminating back and other injuries. All steel constructed tow dollies are sturdy, but weight continues to be an issue. Thus, the need remains for an improved self-loading tow dolly configuration that is not only sturdy, but has the added benefit of weight reduction. It is an object of my invention to provide a self-loading tow dolly that solves this problem.
Because currently available self-loading tow dollies are welded together it is not possible for a tow truck operator to easily replace or fix a tow dolly that becomes damaged. Should a current tow dolly run against a curb and bend a spindle of one of the dolly's wheels the spindle assembly must be cut from the dolly and a new one welded in place. Because these cutting and welding operations require the use of metal working equipment that a tow truck operator typically does not have, the repair has to be done by a welding shop, which is time consuming and expensive. There is thus a need for self-loading tow dollies having modular components that can be replaced without resorting to a torch, saw, plasma cutter, and welder. This is particularly true in emergency situations such as emergency tows and for clearing wreckage from a jammed freeway. Thus, the need remains for an improved self-loading tow dolly configuration that is not only sturdy and lightweight, but also has modular components that can be readily replaced. Accordingly, it is a further object of my invention to provide a self-loading tow dolly that solves these problems.
Currently available self-loading tow dollies have rotating parts that require lubrication to reduce wear. For example, U.S. Pat. No. 5,941,675 to Orr shows grease fittings, 46 and 53 in FIG. 8, used to introduce a thin film of grease about pins 42 and 51. Because there is no lubrication reservoir for grease near or about pins 42 and 51 grease does not coat the entire bearing surface and is hence subject to moisture and rust causing component to seize up. There is thus a need for a self-loading tow dolly that accepts a 360 degree lubrication application to its rotating components. It is another object of my invention to provide a self-loading tow dolly that solves this problem.